1. Field of the Invention
The present invention relates to a method for manufacturing a liquid discharge head for discharging a liquid, and more particularly, to a method for manufacturing an ink jet recording head for performing recording by discharging ink to a recording medium.
2. Description of the Related Art
An ink jet recording head employed in an ink jet recording system is an example of a liquid discharge head used for discharging a liquid. The ink jet recording system discharges ink to a recording medium and performs recording. The ink jet recording head includes an ink flow path, a discharge energy generation unit provided at apart of the ink flow path, and a minute ink discharge port (it is referred to as an orifice) for discharging ink by generated energy.
U.S. Patent Publication No. 2007/0099121 discusses a method for manufacturing such a liquid discharge head. In the method, a pattern layer, which is a mold for a flow path, is formed on a substrate using a photosensitive material. The substrate includes a discharge energy generation unit. A flow path wall member is provided on the pattern layer, and then a space to become the flow path is formed by removing the pattern layer.
For the above described pattern which becomes the mold of the flow path, a positive photosensitive resin is used, and a photolithography method is used for patterning of the positive photosensitive resin. In exposing the positive photosensitive resin, an exposure apparatus that collectively exposes an entire substrate at a magnification of 1:1 is used due to a necessary amount of exposure.
However, the method for manufacturing a liquid discharge head discussed in U.S. Patent Publication No. 2007/0099121 has the following problems.
Since an exposure apparatus collectively exposes a large object (a positive photosensitive resin) provided on a substrate, positioning accuracy between the object and a mask used for exposing is insufficient. Particularly, when the exposure apparatus exposes the object on a large wafer which is about 8 to 12 inches, a warp or flexure of the substrate or the mask affects the positioning. Thus, the alignment accuracy between the mask and the object varies in the same substrate or varies for every substrate to be exposed.
Generally, a main chain decomposition type resin is used as the positive photosensitive resin. However, the main chain decomposition type positive photosensitive resin mostly has low sensitivity to ultraviolet light, so that the exposure apparatus needs to emit a large amount of energy to generate an enough decomposition reaction. Therefore, non-uniform heat expansion is caused between the mask and the substrate by the heat generation during an exposure operation, and resolution and alignment accuracy thus could be decreased. As a result, position deviation between the energy generating unit and the pattern that becomes the flow path occurs, and the pattern of the flow path may not be formed at a desired position of the substrate.
On the other hand, inventors found out in examination that the method described in U.S. Patent Publication No. 2007/0099121 may not form a discharge port having a desired shape when the discharge port is formed at the flow path wall member by using i-line light. The light used for the exposure reaches the substrate, is reflected on the substrate surface, passes through the pattern of the mold of the flow path, and then reaches the resin of the flow path wall configuring member. It was found out that a shape of the discharge port is varied from a desired one affected by such a path of the light.